Most likely that fridge has an electronic control that determines when the motor comes on and when it doesn't (to save electricity and make the fridge more energy efficient), and that's probably what that third wire is for (to control the motor and maybe it's speed, too).
The spinning of the motor impeller causes a blip on your volt meter only because you're using that motor as a generator when you spin it manually, so I'd call that normal.
If you don't get any further responses from the folks in this forum, it's probably because they're simply not familiar enough with your particular fridge to answer your questions. But, there are self help forums at both:
Appliance411 - Appliance Purchasing, Appliance Service and Appliance Repair Parts Information Center for Major Home Appliances
Appliance repairs, Appliancehelp, Appliances, repairs to dryers washers dishwashers fridges repairs microwaves ge maytag kenmore frigidaire westinghouse inglis, appliance how to take apart information, purchasing an appliance help, model number help,
Both of those sites are owned and operated by appliance repair technicians and both have appliance repair Q&A forums where those techs answer questions from people like yourself. But, as appliance repair technicians, they would be much more familiar with your particular model of fridge.
You'll probably have to register your name and e-mail address again at each of those sites, tho.